The present invention relates to a series of steps extending from the sizing of yarns to the treatment of waste water from the scouring, and more particularly to a process of sizing a warp in good work efficiency, weaving into cloth in high efficiency, smoothly desizing and treating waste water from sizing and washing steps with ease.
Polyvinyl alcohol having a degree of hydrolysis of about 88% by mole or more is employed as a warp sizing agent, since it is soluble in water and has good film-forming property and also the desizing can be made by a hot water. However, since such a polyvinyl alcohol extremely lacks in adhesion to hydrophobic fibers, it is usually employed in combination with acrylic resins, when used as a sizing agent for hydrophobic fibers such as polyester filament. The thus formulated sizing agent is also insufficient and has the defects that the binding property is poor, and that size shedding on loom is not disregarded, and particularly that size shedding accumulated in reed dents absorbs moisture and shows the gum up tendency.
On the other hand, it is reported in Japanese patent unexamined early publication No. 60796/1976 that when polyvinyl alcohol of which the degree of hydrolysis is not more than 85% by mole, particularly 79% to 80% by mole and the cloud point of the aqueous solution is not more than 40.degree. C. is employed as a sizing agent, it can be deposited by merely heating the desizing waste water to more than 40.degree. C. and 35% to 45% by weight of the employed polyvinyl alcohol can be recovered. Such a polyvinyl alcohol is soluble in cold water, but deposits under the temperature on preparing the sizing liquid or on sizing. Therefore, it is impossible to conduct uniform sizing and in its turn this exerts a bad influence upon size shedding and weaving.